The croc is a Disney character? I don't recall him from the movie & the Disney wikia didn't turn up anything. If anything, I think it reflects on how Square designs original characters. The ones in VCast: parrot, crocodile, mummy, merchant; they FEEL like Disney characters. They fit into the worlds so naturally one could mistake them for genuine articles. You NEVER get that from Nomura, he's not even trying. VCast is like an insight on an alternate timeline where they took an entirely different approach with KH.
Well given the fact that in the original KH, there are only 3 categories of characters that it could fall under (it most definitely is NOT a heartless) those being Disney, Final Fantasy and original character (which is often considered more or less a subset of Final Fantasy; that opinion is not universal) it's more in line with being a Disney character since Disney has experience with crocs before

(also worth noting that it's in a world that branches off of England, in much the same way Neverland does)
Given the fact that it appears in a world closely related to Peter Pan due to both stories originating in England, and the fact that both Alice in Wonderland and Peter Pan star Katherine Beaumont as Alice and Wendy respectively, I've come up with a theory. It's not a GOOD theory, but worth noting.
So KH V-cast is essentially a dream Sora is having in the gummi ship right? that's the whole plot of the game and fits seamlessly into the KH timeline if it was canon (it isn't but it very easily could be, just say that the events happen before SDG arrive at Hollow Bastion). Assuming that it's set before the penultimate world, that means Sora Donald and Goofy have visited every world besides the final two in KH, and thus know of Agrabah and Wonderland as they've physically been there. Swashbuckler's Island is pretty straightforward, Sora was always interested in pirates and his subconscious created a "world" based off of what he knew of them. Given the fact that Destiny Islands is situated in what I assume is a colossal ocean and the actual town seems pretty close to our modern world, it's likely that they had a substantial maritime history, with all of the trappings that come with it. The kids play pirate with wooden swords, Sora expresses an interest in sailing a pirate ship in Port Royal, and they even build a raft to set out on an adventure. So it's not too farfetched to assume that it's a world solely created from his memories and knowledge of deserted islands and swashbucklers.
As for the crocodile in Wonderland, that's simple really. Assuming it is between Neverland and Hollow Bastion on the timeline as I stated earlier, Sora and co. already experienced their near death experience with Tick Tock acting as their executioner before learning to fly. Whether or not Destiny Islands folk have any concept of large semi aquatic reptiles is a discussion for another day, but Sora definitely has seen one and thus his mind is aware of what constitutes a crocodile. Since V-cast is a dream however, it's a realm where nearly anything can happen (a proto-realm of sleep before 3D was a twinkle in Nomura's eye) and reality itself isn't a guaranteed constant. So Sora can meet with people and animals in V-cast that he is aware of, but in differing circumstances than what he initially saw in when he was awake. Thus you've got an abnormally colored crocodile boss in Wonderland (a world already made of a dream itself) where there wasn't one before.
This concludes my Ted Talk, goodnight.